View Full Version : Adding hydronic radient heat to a turn small 100 year old church.
12-26-2011, 02:59 PM
So I bought a church, with the intention of making it my home.
I'm thinking radient heat is definitely the way to go but would love to bounce some ideas off people before I go beyond the brain storming phase.
Some info about the structure:
it's a church
It's in portland Oregon
It's about 1200 square feet on the main floor with 1200 hundred more feet of daylight basement underneath
there is not a lick of insulation in the building
the peak ceiling height is about 22' on the main floor and 8' continuous in the basement.
My initial thought is put a staple system up between the joists for heating the main floor and thats about as far as I got before running into allot of questions.
Mostly I'm concerned about how to heat the basement, it will be a finished space and the location of the bedrooms and the restrooms. I'm leaning towards using radiators in this space as opposed to putting radient in the floor. I'm 6'4" so im sensitive to any loss in ceiling height in this space. I know that buy having a mixture of radient floor heat and radiators I'll need a boiler, heat exchanger, mixing valve and such, which seems complicated but not daunting. another thought is to put hydronic heating loops in the walls of the basement, allowing me to use one of the fancy hyper efficient hot water heaters as a heat source. The final and least appealing idea is to jack hammer out the basement floor and install an in slab system without losing too much ceiling height.
any thoughts? I'd really appreciate any advice I can get.
A little about myself, if it helps;
I have a degree in mechanical engineering but haven't done serious calculations in ten years as I have been working as an officer in the engine rooms of large tanker and container ships.
This gives me the ability to speak geek and the fabrication skills to tackle most anything. Unfortunately this combination may allow me to get myself way over my head, and spend a bunch of money on equipment that ultimately won't play nice together. My intention is to figure out mostly what kind of system I want, have someone who really knows what they're doing design it, and then install it myself.
Staple ups require significantly higher water temps than slabs or above-the-stubfloor radiant systems (eg WarmBoard), or under-floor radiant using heavy extrusions (not bent/stamped sheet metal) as the heat exchanger between the tubing & subfloor.
First things first- count on AIR SEALING, then INSULATING the place, including the foundation walls (and put at least R15 under the new slab, if you jackhammer out the floor), and do a Manual-J type heat loss calculation of what the design condition heat load of building will be after the insulation project is done. That will determine how much burner and what type of radiation you'd need to run it all at a single temp that's low enough to be handled by a water heater. It's possible that a suspended-tube or simple staple up would require higher water temps than the operational rating temp PEX, but with extrusions it's likely that you'd still make it with 130F water, with at least some condensing-efficiency out of the water heater or boiler.
You might consider going with a radiant ceiling in the basement rather than a slab to simplify things, since that would be more responsive and likely closer in temperature requirements to the first-floor radiant floor than a slab would be, and more efficient, easier to implement, and less risky than radiant walls. (Hanging a picture in the wrong spot on a radiant wall can be a real disaster when the heating system leaks.)
Even as a DIY project it's best to find a competent hydronic designer for the heating system (no quickie web-based radiant supplier need apply.) You'll save more on hardware and fuel by paying for a good design than you'd save by skipping that step. If you can get the temp requirements low enough, a condensing tank type HW heater (Vertex or Polaris) would be a better choice than a modulating tankless, since it's inherently self-buffered and won't short cycle if you decide to break it up into several smaller zones even with low-mass radiation like staple-ups.
12-27-2011, 12:27 PM
I would go pipes on the main floor and sleepers and cement over it all. Ceiling fans, obviously. Basement seems like radiators would be easiest.
How are you going to insulate this beast? Stone construction? Seismic? Polaris sounds good.
Cement floors are hard, not as comfy under foot- a lot of people end up putting carpeting over them which defeats the lower-temp efficiencies that a gypcrete/concrete solution would otherwise allow. It's usually cheaper than a WarmBoard solution though.
But without a heat load analysis it's hard to say for sure if any of the above would be sufficient on design-day, especially if left uninsulated. Go with air sealing & insulating & doing the heat load math first. Recommendations for particular radiation types or heating-water source are WAY premature. For all we know this place is a leaky sieve (most churches are), with a design day heat load 2x the output of a Polaris and with a BTU/square-foot requirement above what can be reasonably delivered with radiant floor at ANY water temperature.
12-27-2011, 01:26 PM
I use sleepers/ cement and then wood over it all. Soft enough and seems to give plenty of heat transfer.
12-27-2011, 06:09 PM
Thanks for the replies, It's good to get some feedback beyond the echo in my own skull.
Yes I do intend to insulate but not as much as people might hope, current plans are to insulate the basement with rigid foam on all the walls and the floor. The attic I plan on rolling out two layers of fiberglass batt. I don't plan on insulating the the walls of the main floor as I don't have the money or time to pull down all the siding insulate and install a proper vapor barrier and re-install the siding. As for the window on the main floor I don't want to replace those either, they're actually in amazing shape, so I hope to go old school with proper wooden framed storm windows during the winter months. oh, and of course i'm a fiend with a caulking gun finding and plugging all air leaks.
In response to dana,
thanks for the reply I guess was a little sloppy with my terminology when I said staple up, I was describing in my own head an under floor system with heat transfer plates. As for the warm board it looks like a cool product but I'm really trying to avoid pulling up 1200 square feet of stunning quarter sawn old growth fir just to have to lay it back down over a new fancy subfloor. the warm board may be an option in the basement. I'd hesitant about a radient ceiling due to issues of comfort. I hear you, on having a pro do a heat loss analysis, I did some in school ten years ago but wouldn't have a clue where to start now. Any ball park ideas what a report like that costs?
In response to ballvalve,
thanks for the interest, the building has a cement foundation, and is framed with full dimension clear old growth two by fours, it has lath and plaster walls that are in good shape. the exterior is clapboard, with tar paper and sheathing underneath.
As for seismic, you can get insurance if you bolt the sill down to the foundation, which I plan to do. I don't know of any other seismic upgrades to stick built houses in my area.
once again thanks for the interest
12-28-2011, 11:29 AM
Blown-in cellulose in the attic gets you more bang for the buck than fiberglass and is significantly better stopping convective losses. You may be able to do that in the walls as well by either having a couple of holes in each stud bay or pulling off a couple of rows of siding to do it from outside.
Air sealing the ceiling/attic floor with spot foaming & caulk at every electrical & plumbing penetration & every crack or hole prior to insulating will be key to keeping the roof decking from getting mold. Air sealing is at least as important as insulating from a thermal performance too. Buy a real foam gun that takes the 20-22 oz 1-part foam cans- you'll spend less on foam and it's easier/better than the plastic-straw 12-16oz cans you get at box stores. (They're available online, if you can't find it at distributors in your area.)
Low density fiberglass (particularly batting) is a lousy way to insulate an attic, since it has huge losses from convection currents within the fiber layer in winter that increases with greater temperature differences (it has the lowest effective-R when you need it the most) and is semi translucent to infra red making it less effective in summer. Batt installations inevitably end up with gaps & compressions too. The convection losses can be reduced considerably by adding a top side air-barrier, but that air-barrier has to be vapor-open to water vapor or you'll end up with condensation at that layer. (Housewraps such as Tyvek or Typar work well. Don't use radiant barrier or poly sheeting, as they are true vapor barriers.) Rock wool is denser and more air retardent, but cellulose at any density is even more air-retardent, and doesn't need a top side air-barrier. (Rodent's won't nest in it either, unlike fiberglass.) It's also opaque to infra-red, and functions well in summer too. The downside is that it's ~1.8-2.2lbs per cubic foot, and if the joists are skinny & widely spaced going high-R may require a loading analysis (something an ME might be able to handle. :-) ) R50 requires a ~14" settled depth (~16" initial- give it a decade and it'll settle), so figure on ~2-2.5lbs/ square foot. Blown insulation fills in all voids, reducing convective thermal by passing. There are no rocket-scientist wasting their careers blowing insulation in attics- this is a fairly straightforward DIY project with a rental blower, and with 2 people it goes very quickly. (One to open bags & fill the hopper, the other to blow the insulation.)
Blowing insulation into the wall cavities without gutting or stripping either the interior or exterior can also be a DIY project, but it may be worth paying a pro. If you "dense pack" the goods it effectively air seals the wall cavities (from a thermal, but not moisture point of view.) With dense-packed new-school superfine fiberglass at 1.8lbs/cubic foot density you end up with a slightly higher R value than with cellulose at 3-3.5lbs but with cellulose the material itself is a hygric buffer for moisture drives, and in a Portland climate you wouldn't need an interior vapor retarder of any kind (not even kraft paper)- latex paint on the interior would be enough. (This is done successfully with cellulose all the time in New England, which is much colder ==> higher risk for condensation at the sheathing than in Portland OR.) Cellulose is air-retardent enough that you can get away with cheaper mid-density "2-hole" installation if the budget is tight, but on a tall balloon-framed building you'd need to top it off in a couple of decades due to settling, whereas dense-packed it would not have that issue. When dealing with cellulose, insist on "borate only, sulfate free" material. Sulfated fire retardents are cheap, but corrosive to metals when wet, and are banned in some countries.
Lower density fiberglass is not an option in walls due to convective loss issues. (If ever installing batts, go with the "cathedral ceiling" type batts, which are 2x the density of standard cheapies. R21 high density batts in a 2x6 framing outperforms low-density R22s (and WAY outperform R19s, which has the same amount of material as an R13 batt for 2x4s.) With full dimension timbers standard batt widths & depths are all wrong too, and if you leave a space air can convect around the batt or form a mini-flue to drive infiltration losses. Blown goods WILL fill every nook, cranny and irregularity.
If the storm windows are tight and in good shape, tighten up the main windows and it'll outperform a middle-of the road replacement window. The sash weight pockets can be an air-leak and low-R issue though, and it may be worth pulling them and blowing those full of insulation at some point. Reglazing the storms with low-E glazing (or getting new low-E storms) is also worth considering.
Good deals can sometimes be had on reclaimed foam insulation (http://portland.craigslist.org/clc/mat/2764933868.html) from roofing, which can cut the cost of insulating the foundation walls immensely. In my area there are dealers, but craigslist searched will often come up with something. Be sure to use only fiber-faced or unfaced goods below grade, and if using XPS (rather than EPS or iso) limit the thickness to 2". A building this vintage does not have a capillary break at the footing, nor at the foundation sill, and groundwater WILL wick up into the wall, and needs to dry toward the interior on the below grade sections. If the rigid foam is too vapor tight (foil or poly facers, or lower-permeance goods like XPS if applied too thick) the moisture ends up in the foundation sill creating rot conditions. R5 XPS between an interior 2x4 studwall with unfaced rock wool or HD fiberglass batts delivers an honest R15 whole-wall R. Similar performance can be had w2.5" fiber faced polyiso or 4" of unfaced EPS, held in place with 1x furring through-screwed to the foundation with tapcons, mounting the wallboard to the furring. Whichever way you go, do not use any type of vapor retarder (other than the foam) anywhere in the stackup. You can use 1-2" of closed cell spray polyurethane to seal & insulate the foundation sill & band joist (Tiger Foam, FrothPak, or Fomo-Foam, etc.) to the wall insulation foam, or cut'n'cobble rigid foam in there, sealing the seams with 1-part foam.
A room-by-room Manual-J type heat-loss calc from a qualified pro would likely cost ~$250-500, depending on just how complex it is, and how busy they are. Some heating contractors would roll that into the cost of the project if they win the bid, but would otherwise charge it as a standalone service.
Saving the quarter sawn fir is the right thing to do. To keep the water temp requirements low use extrusions, not sheet metal for the heat transfer plates:
These are substantially more expensive (~1.60/linear foot, and you'd normally use two runs per joist bay with 16" o.c. joists) than the sheet metal variants, but are also much more effective.
Fears of radiant ceiling becoming uncomfortable are overblown, as long as you insulate the foundation walls and air-seal reasonably. The heat loads in Portland OR are relatively modest, with heating design temps in the ~20F range, which means the surface temp of the ceilings probably won't exceed 75F very often. In places like the upper midwest or Canadian midwest where the design temps are -15F and lower peak heat loads are ~2x what you'd normally get in Portland requiring higher surface temps that can be oppressive even with 10' ceilings. In my area (central MA) heating design temps are around 0F, and in reasonably tight insulated homes radiant ceilings are just fine at 8', but might feel oppressive on design day if you go any lower than that. With your shoes on radiant ceilings are about as cushy as radiant floors, but never has the cruisin' in yer socks appeal that radiant floors can deliver. Low temp panel radiators can get you there too, and are also quite comfortable, if you want to avoid demolishing and replacing the slab.
12-28-2011, 01:16 PM
Nice church. I must admit that I once had even larger ambitions for a defunct building....
I once bought a Synagogue in Slovakia. You may have heard the Germans swapped Jews for not killing the Slovaks. Dirty little story. Left a lot of empty buildings behind.
$15,000. Covered a city block, had a bunch of guys buried in the walls of the entry, and had a mosaic floor that covered about an acre. The ceillings maybe 120' up? were fully covered with detailed paintings and symbols that 200 artists could not reproduce in 50 years. The Communists used it as a wool storage barn! The bullet holes inside and outside were quite a poignant reminder of a world gone mad. All cut stone blocks, like the pyramids.
Had to let it go, as the "preservation" commitee wouldnt allow any removal of items [came with partially shot out detailed stain glass of a few acres] And they valued it for "replacement" cost -HAH! not purchase cost. I did pass the information to the last Rabbi in Slovakia, who knew not of its existence and last I heard was going to get title back. Hopefully some rich jew will make a museum out of it or move it to New York.
Here is one similiar - still looking for 'mine'. http://www.slovak-jewish-heritage.org/site_of_the_month.html?&L=1Bratislavsk%C3%83%C2%83%C3%82%C2%83%C3%83%C2%82 %C3%82%C2%A1arcidiec%C3%83%C2%83%C3%82%C2%83%C3%83 %C2%82%C3%82%C2%A9znacharita.%5Bonline
Okay you restorers, heres the one for "my old house": http://sk.wikipedia.org/wiki/Synag%C3%B3ga_v_Byt%C4%8Di
I realize that my prior post has a whole lot o' stuff, but the goal is to get the peak heat loads down to where the water temps for a radiant solution that are in a domestic-hot water/condensing boil range. On a building that tall air sealing will be critical, as will insulating the walls. Every wall cavity is essentially a flue with a significant stack-effect pressure driving infiltration, and the taller the framing, the higher the stack pressure. Insulating the walls reduces the flow, dense packing the walls reduces it by well over 90%
Before insulating the attic it's important to have already done most of air sealing, and it's worth measuring & rectifying with a blower-door test. No matter how good you are with caulking & foam guns, there WILL be repairable leaks (lots of them) that can be discovered only with blower doors and infra-red imaging. The first $1000 of air sealing can easily be worth more than the next $2000 of insulation. First fix everything you can find (start with big holes first, such as flues & chases that run from the basement to the attic, then other ceiling penetrations, then the foundation sill and any wall penetrations into the basement), then find an insulation contractor who specializes in air-sealing who uses blower doors and IR cameras. If you can get this thing under 5ACH/50 (that five air changes per hour at 50 pascals pressure) on the first pass you're genius, but it can probably be brought under 3ACH/50 without stripping the walls and foaming the sheathing with closed-cell.
01-02-2012, 01:56 PM
First, a heat load analysis from which all other information about retrofitting radiant floor heating to an old building is properly derived. Thank goodness you are not half-cocked like so many.
Once you have the current heat load you can determine how cost effective each of the many suggestions might be. Most retrofit radiant heating systems involve older homes
with beautiful existing wood floors. Though it may require the use of relatively high design water temperatures, this is not necessarily the case, nor a fatal flaw in design philosophy.
First, figure out what you can afford, then from a realistic budget, what can be done, then proceed with confidence whether you DIY or contract the radiant floor to others. I design
sub-floor heating systems for homes/churches like yours and usually use European style steel panel radiators for lower levels and second floors where ceiling height is a concern.
Find a professional HVAC designer with some radiant floor heating experience before you start ordering product over the Internet.